98 DWIGHT 



III. EARLY PLUMAGES AND MOULTS OF 

 YOUNG BIRDS 



The plumages and moults of young birds differ so much from 

 those of adults as to deserve further elucidation. Although 

 feathers of adult structure are acquired and worn during the 

 first winter after leaving the egg there are two antecedent stages 

 of plumage in all species and in some, several subsequent stages 

 indefinitely classed as immature, all of which are but imper- 

 fectly understood. 



A bird on emerging from the egg may be absolutely naked, 

 of which the Woodpeckers furnish an example, scantily clothed 

 with downy tufts as in most of the Perching Birds, or com- 

 pletely invested with downy growth as in the Ducks, the Water 

 Birds and the Birds of Prey, The structure of this " nest-down" 

 varies greatly in the different groups of birds, and it is always 

 replaced by several other plumages before that of the adult bird 

 is assumed. Among the Passeres, which is the only group 

 here under consideration, the downy growth is present (at least 

 part of it is) before the chick hatches. It is found at only a few 

 points. A longitudinal row or two is found above the eyes 

 corresponding nearly to the location of the superciliary stripes, 

 several rows occur on the occiput and nape and tufts are found 

 on the dorsal, humeral and lumbar tracts as well as filaments at 

 the tips of the secondaries and their coverts. No down is 

 found at the tips of the primaries or rectrices nor does it occur 

 on the ventral tract in any of the Passerine species I have exam- 

 ined, the protection of the nest perhaps obviating its necessity 

 below. A nest full of young birds gives one the impression that 

 they are covered with a fluffy blanket of down. The distribution 

 of these downy filaments may be dimly seen by consulting plate 

 III, and their microscopic structure is shown by plate V which 

 illustrates for the first time by means of photography the exact 

 structure of this peculiar plumage. These peculiar feathers are 

 interesting under the microscope being long weak filaments with 

 a few short lateral branches. They are gathered into a bundle 

 at the tip of the new feather, which takes their place and they 



